A hoard of pikeys who go around doing chavvy behaviour. Typically proletariat these underlings try to terrorise the streets of cities with ASBOesque behaviour. Often being very 'try hard'.

Charles: "James look at those hooded youths"
James: "Youths? They appear to be are age?"
Charles "You know what I mean, pikeys, rif raf, underlings, proletariat."
James: "Yes, they seem to have formed some kind of mandem"

Definition is Jamaican/Patois slang meaning - "them men over there" literally, but is used to describe the men in society, can be used for random people/friends - mostly used for friends/acquaintances these days in London.